The invention relates to a solid fuel propulsion system for a ram jet rocket.
Solid fuel propulsion systems for ram jet rockets are known which are provided with a combustion chamber having a tubular casing and a gas generator disposed upstream from the combustion chamber for generation of a combustible gas from a solid fuel. The gas generator is surrounded by a tubular casing. A gas-stream regulator unit for regulation of the flow of the combustible gas from the gas generator to the combustion chamber is disposed between the gas generator and the combustion chamber.
In these known solid fuel propulsion systems, the gas generator and the combustion chamber are each formed as closed pressure vessels with elliptically dished heads. The gas stream regulator unit is disposed between the gas generator and the combustion chamber and in the event of deformation of the pressure heads of the gas generator and the combustion chamber due to internal pressure and heat during operation of the propulsion system, the function of the gas flow regulator unit is adversely influenced.
An object of the invention is to provide a solid fuel propulsion system for a ram jet rocket which is reliable in operation of the gas flow regulator unit.
This and further objects are achieved by a solid fuel propulsion system according to the invention, which comprises a combustion chamber having an outer tubular casing, a gas generator disposed downstream of said combustion chamber for generating a combustible gas from a solid fuel in said gas generator, said gas generator having an outer tubular casing, and gas flow regulator disposed between said combustion chamber and said gas generator for regulating a stream of combustion gas from said gas generator to said combustion chamber, a middle section being secured between said gas generator and said combustion chamber and supporting said gas flow regulator therein. Load resisting connections secure said middle section to said tubular casings of said gas generator and said combustion chamber, said middle section having a first pressure head sealing the combustion chamber from the middle section and a second pressure head sealing the gas generator from the middle section. The middle section has a base unit engaged between said pressure heads and braces said pressure heads, the gas flow regulator being housed in the base unit.
According to one embodiment of the invention, the middle section is surrounded by a tubular casing portion.
Preferably, the casing portion forms a part of the structure joining the casings of the gas generator and the combustion chamber.
Preferably, the casing of the gas generator, the casing portion of the middle section and the casing of the combustion chamber have substantially the same diameter.
According to the preferred embodiment of the invention, it is provided that the casings of the gas generator, combustion chamber and middle section are stepped annularly at their adjoining ends and are pushed one into the other and tightly interfitted by the load resistant connections.
In this embodiment, the load resistant connections between the casings is preferably formed by a coil spring system tightly embracing the engaged ends of the casings.
The casings of the gas generator and the combustion chamber which are pushed one into the other at their ends advantageously form the casing portion of the middle section and they are securely coupled together by the load resistant connection. In this case, the middle section between the casings of the gas generator and the combustion chamber is preferably positioned in an axial direction by shoulder rings interlocking therewith.
According to another preferred embodiment of the invention, the base unit of the middle section is formed as an annular member, and the pressure heads are formed as annular caps of U-shape mounted on the annular member. The U-shape of the caps forms cylindrical rims constituting reinforcements for the caps.
In the aforesaid embodiment, it is preferable that the casings of the gas generator and the combustion chamber have an annularly stepped configuration and are pushed one into the other and secured by a load-resisting connection. The interfitted casings form a tubular casing portion surrounding the middle section, and shoulder rings are provided on the casings of the gas generator and the combustion chamber to brace and secure the middle section in the longitudinal direction. In an improvement, the shoulder rings on the casings of the gas generator and the combustion chamber are engaged against shoulders formed on the annular caps of the middle section.
Preferably, circumferential scaling rings forming a hermetic seal are disposed between the outer cylindrical rims of the annular caps and the casings of the combustion chamber and the gas generator.
According to a highly advantageous improvement of the invention, beat shields are provided on the pressure heads to protect them against thermal effects. These heat shields are preferably made of thermally ablative material, such as a silicone-base material.
Preferably, the base unit is made of a lightweight metal, especially aluminum, or of a high-strength ceramic, especially reinforced with carbon fibers.
The pressure heads are preferably made of steel or high-strength ceramic, preferably reinforced with carbon fibers.
According to another preferred improvement of the invention, a means for active cooling is provided by using he heat of evaporation of a liquid, such as water, said means being provided in the base unit and/or on the pressure heads.
According to another embodiment of the invention, a gas guide is provided in the middle section and extends in the longitudinal direction of the propulsion system, preferably parallel to the axis thereof, to provide for passage of the gas flow from the gas generator to the combustion chamber. The gas guide is preferably made of molybdenum.
According to another improvement of the invention, the gas guide is surrounded by an insulating jacket to prevent heat transfer with the interior of the middle section. The prevention of heat transfer can be improved by disposing the insulating jacket between the outer circumference of the gas guide and a steel liner surrounding the insulating jacket. Advantageously, the gas-stream regulator unit contains a final control clement which regulates the mass flow of the gas stream through the gas guide.
According to another embodiment of the invention, the gas stream regulator unit contains an actuator, which is mounted in the base unit of the middle section and which is coupled to the final control element said final control element being disposed outside the base unit and cooperating with a regulator nozzle provided at an end of the gas guide for the purpose of regulating the gas stream through the gas guide.
According to another improvement of the invention, the middle section contains a pressure neutral zone, which is sealed from the gas generator and the combustion chamber by sealing elements, and through which measuring and supply lines pass into the interior of the base unit.
Advantageously, the pressure neutral zone is defined by the sealing rings disposed between the annular caps and the casings of the combustion chamber and the gas generator.
Advantageously, the middle section is constructed as a module which is a self-contained functional unit.